Light emitting diodes (“LEDs”) have many advantages over conventional light sources, such as incandescent, halogen and fluorescent lamps. These advantages include longer operating life, lower power consumption and smaller size. Consequently, conventional light sources are increasingly being replaced with LEDs in traditional lighting applications. As an example, LEDs are currently being used in flashlights, traffic signal lights, automotive exterior and interior lights and display devices.
A typical LED includes an LED die mounted on a substrate, such as a leadframe, and encapsulated in a molded lamp package. Since the light output of an LED is limited, the LED die may be mounted in a reflector cup formed on the substrate to collect the light emitted by the LED die and direct the light upward toward the top of the transparent lamp package. Moreover, the transparent lamp package of the LED may have a domed top, which functions as a lens to focus the light emitted from the LED die.
Different LED-based light source devices have been developed for various lighting applications. A typical LED-based light source device includes a number of LEDs to produce the desired illumination. These LEDs are usually mounted on a printed circuit board (PCB). An important design consideration of an LED-based light source device is heat management. When activated to generate light, an LED die produces a significant amount of heat, which is compounded when there are multiple LED dies in a small area. Unless properly dissipated, the collective heat generated by the LED dies can degrade the performance of the LED dies and even damage the light source device. Thus, the heat dissipation efficiency of the LED-based light source device may limit the density of LED dies that can be included in the device and/or limit the amount of current used to drive the LED dies.
In view of these concerns, there is a need for an LED-based light source device with increased heat dissipation efficiency so that the device can have a higher density of LED dies and/or the LED dies can be driven with higher current.